1. Field of the Invention
The present invention relates to a molding machine for injection molding of tooth brushes from two or more different molding material components with inmolded fibre or bristle tufts.
2. Description of the Prior Art
Conventional tooth brushes have a brush body which is injection molded in a single molding step from an appropriate molding material. There is an increasing demand for tooth brushes with a brush body made from different materials. For example, the brush body may have particular zones for enhancement of the grip or feeling, or decorative elements incorporated therein. These elements are molded from a material which is different in nature, color, hardness, or other properties, from the molding material wherefrom the base part of the brush body is molded. In order to produce such brush bodies by injection molding, the molding must be carried out with at least two different molding material components in at least two injecting stations, each of these injecting stations being associated with a different one of the molding material components.
In EP-0 504 571 A1 a molding machine for injection molding of tooth brushes from two different molding material components is disclosed. The machine comprises two injecting stations each associated with a different one of the two components. The first injecting station has a mold cavity corresponding in shape to the base part of the tooth brush bodies, including a handle portion and a head portion. The second injecting station has a mold cavity corresponding in shape to the requirements of the second molding material component. Each mold cavity is defined by a fixed mold part and a movable mold part. The fixed mold part has a recess, and a mold insert part fits into the recess to complete the fixed mold part. The insert part is mounted on a movable carrier and has an extension which, when the mold is closed, projects into the mold cavity defined therebetween. The carrier is used to transfer the blank molded in the first injecting station to the cavity of the second injecting station, the blank being held on the carrier by the extension of the mold insert part penetrating into the blank. Only the cavity of the first injecting station needs to be provided with an array of pins extending into the head portion of the cavity to provide the molded blank with a pattern of holes for implantation of brush bristles after completion of the molding steps. For a complete manufacture of tooth brushes, the finished brush bodies are then supplied to a conventional brush filling machine where tufts of bristles are forced into the holes of the brush body head portion and fixed therein with a piece of metal, generally referred to as an anchor. The brush filling machine may comprise further processing stations such as bristle trimming, roundening and polishing stations.